Linear motors which work according to the synchronization principle have a primary part developed as a guideway stator on which a secondary part is situated in a freely movable manner. For the propulsion of the secondary part, a traveling magnetic field is generated which moves the secondary part, that is developed using magnets, along by magnetic reciprocal action.
The generation of the traveling field in the stator windings takes place by feeding in a three-phase current of variable frequency which determines the speed of the motion.
The guideway stator is subdivided into individual segments, which each have connected windings. At the connecting points of the segments current-supplying devices are situated, which respectively apply current to the connected segments, which is necessary for the motion.
This form of construction requires a costly design and control of the individual current-supplying devices.
For instance, in German Published Patent Application No. 39 00 511, a linear motor is described having a primary part that has stator poles arranged in series and a secondary part that is movable alongside the primary part.
The coils of the guideway stator have current applied to them by power converters whose frequency and amplitude are controllable by an electronic controller which takes into account the current residence locale of the secondary part, in order to move the secondary part on the primary part. For the propulsion, segments of the primary part are supplied with current by the external control device, whereupon all the secondary parts, which are on one segment of the primary part at this time, move away uniformly.
German Published Patent Application No. 199 22 441 describes a method and a device for operating a magnetic vehicle having a synchronous guideway stator linear motor. A costly, controller is described which controls the supplying of current to the individual winding sections, and with that also the propulsion of the secondary parts. Secondary parts which are located in a similarly controlled region, that can also be composed of several winding sections or segments, are in turn moved away uniformly.
The suitable energizing of the coils or windings of the stator is connected with great expenditure, especially if several secondary parts are supposed to move independently of one another on a guideway stator, which can also be an extended rail system. Oppositely directed propulsion of secondary parts is not possible within one stator segment in the shown related art.